Randomly choose between generators
Examples
one_of(integer_(), character_()) %>% show_example()
#> [1] -2425 -6980 -7116 8755 -2385 -6147 -4026 -3311 171 9779
one_of(constant(NULL), logical_(), prob = c(0.1, 0.9)) %>% show_example()
#> [1] TRUE FALSE FALSE TRUE FALSE FALSE TRUE